/Engine/Plugins/Media/MediaIOFramework/Source/MediaIOCore/Public/MediaIOCoreTextureSampleConverter.h
Don't forget to call FMediaIOTextureSampleConverter::Convert(...) from the child classes to trigger JITR pipeline. This is the place where late sample picking is actually happens.
class FMediaIOCoreTextureSampleConverter : public [IMediaTextureSampleConverter](API\Runtime\Media\IMediaTextureSampleConverter)